In an internal combustion engine, it is known for a fuel pump to supply fuel at high-pressure for delivery to each cylinder of the engine by means of a dedicated fuel injector. Typically, the fuel injector is received within a bore provided in a cylinder head of the cylinder, and a connector (or fuel lance) is used to provide a fluid connection between the fuel injector and a fuel supply line (or pipe) from a fuel pump or accumulator volume/common rail.
Such an arrangement is known from EP 0569727, as shown in FIG. 1. A connector 1 is disposed within a transverse bore 3 in a cylinder head 5 that intersects with a bore 7, in which the injection nozzle 9 is housed. The connector 1 has a spherical taper 11 on its outlet end to form a fluid tight seal against a lateral seating face 13 on the injection nozzle 9 when it is clamped in place by means of a retaining screw 15. To firmly seal the connector 1 against the injection nozzle 9, the retaining screw 15 has an external screw thread that cooperates with an internal screw thread provided in the transverse bore 3 of the cylinder head 5. A spherical shoulder 17 is also provided on the connector 1, against which the retaining screw 15 presses when tightened. As clearly indicated, the inlet end section 19 of connector 1 projects beyond the retaining screw 15 and the cylinder head 5 in order that the fuel pipe 21 may be clamped in place. The inlet end section 19 is provided with an external thread 23 onto which a female pipe nut 25 is screwed to clamp the fuel pipe 21 to the end of the connector 1. The inlet end section 19 of the connector 1 is further provided with a female conical seating surface 27 about the fuel passage 29 that passes through the connector 1, against which a male conical seating surface 31 of the fuel pipe 21 seals when the pipe nut 25 is tightened.
However, the prior art fuel supply line arrangements for connecting a fuel pipe to an injection nozzle have a number of disadvantages. By way of example, the shoulder (or flange) on the connector that is required to transfer the load from the retaining screw to the conical (or spherical) sealing face at the injector end of the connector adds to the complexity of manufacture and prohibits the use of a smaller diameter connector, which would reduce the cost of manufacture. Furthermore, the prior art connectors are typically considerably longer than the length of the bore of the cylinder head, in which they are located. Therefore, the connector extends beyond the cylinder head and takes up a significant amount of space within the engine, which can cause packing conflicts with other components fixed in the region of the cylinders. The length of such prior art connectors also adds to the cost of manufacturing this component. Thus, there is a need for a fuel connector/lance that provides design and manufacturing cost benefits and/or which achieves installation benefits over the prior art.
A further issue with some prior art fuel supply line arrangements, such as that already described, is that a tight seal between the connector and the injection nozzle requires the tightening of a retaining screw into the cylinder head and the transfer of the load from the screw through the connector. This mechanism thus requires the rotation of tightly fitting parts and the friction between the rotating components can lead to the generation of undesirable particles (debris), which could lead to the contamination of fuel and/or the wearing of the components. In addition, an anti-rotation device may be necessary on the connector to prevent it rotating within the cylinder head, further adding to design complexity and manufacturing costs. It would be further desirable to provide a fuel supply line arrangement that reduces or eliminates the requirement for the rotation of components within the cylinder head during assembly and/or disassembly.
The invention relates to a fuel connector or lance that overcomes or at least alleviates at least one of the above-mentioned problems and disadvantages in the prior art, and also to fuel supply line arrangements comprising such a fuel connector or lance.
In broad terms, the invention provides a fuel lance, a fuel lance assembly, and a fuel supply line arrangement that provides all necessary functionality and which provides desirable advantages over the prior art, such as greater simplicity and, therefore, a lower cost of manufacture. It may also avoid prior art design limitations on the size of various parts, such that it takes up less space within the increasingly complex and crowded engine space. In some embodiments, the apparatus of the invention provides functional benefits in terms of reducing component wear and avoiding potential fuel contamination from worn engine components.